A、Its strong currency. B、Its high cost of buying a car. C、Its beautiful environment. D、Its massive immigrants. A短文开头提到，新加坡强有力的货币

Singapore has topped 131 cities globally to become the world’s most expensive city to live this year, according to the Economist Intelligence Unit. The city’s strong currency combined with the high cost of running a car and soaring utility bills contributed to Singapore topping the list It is also the most expensive place in the world to buy clothes.
    Singapore replaces Tokyo, which topped the list last year. Other cities making up the top five most expensive cities to live in are Paris, Oslo, Zurich and Sydney, with Tokyo falling to sixth place. The EIU’s Worldwide Cost of Living Survey is a relocation tool that uses New York City as a base. It looks at more than 400 individual prices. The top 10 cities this year have been dominated by Asian and Australian cities as well as some in Europe. The editor of the report Jon Copestake said, improving sentiment in structurally expensive European cities combined with the continued rise of Asian centers means that these two regions continue to supply most of the world’s most expensive cities. But Asian cities also continue to make up many of the world’s cheapest, especially in the Indian areas. Most Asian cities that top the list are there for mainly higher costs of groceries. Tokyo is still at the top of the list for everyday food items.
20 What contributed to Singapore being one of the world’s most expensive cities to live in?
21 What city topped the list last year?
22 What is the main reason that most Asian cities top the list?